Suggestion: Add methods or parameters to filter the list

[GadgetSteve]

Specifically there are a lot of test. members to the standard library that people probably don't need most of the time, (e.g. when deciding which libraries to include in an executable). I think that it also might be handy to be able to get a list of just the top level libraries.

Taking python 3.8-64 as a test case:

from stdlib_list import stdlib_list
sl = stdlib_list('3.8')
print(len(sl))  # 1766
no_test = [l for l in sl if not l.startswith('test.') and not l == 'test']
print(len(no_test))  # 1062
top_level = {l.split('.')[0] for l in sl}
print(len(top_level))  # 310

I think that it would be great to either have functions or flags on stdlib_list to return the no_test & top_level filtered lists above, (which could possibly be produced more efficiently).